void main() {
  Person p1 = new Person();
  Person p2 = Person();
  print(p1.age);
  print(p1.name);
  p1.eat();
  p2.eat();
  print(p2.age);
  print(p2.name);
}

class Person {
  String? name = "八戒";
  int? age = 20;
  eat() {
    print("吃饭");
  }
}
